Activated carbon has been utilized to purify water, air, and various chemicals through the process of adsorption; however, activated carbon has also been well established as a source of bacteriological contamination. Naturally occurring bacteria inherent to material being purified (water, air, etc.) will inhabit the pore structure of the activated carbon. The result is the periodic need to disinfect the activated carbon to prevent unacceptable levels of these bacteria from exiting the activated carbon in the purified solution. This issue is very prevalent in the water purification industry for applications such as potable water purification. Various processes have been utilized over the years in an attempt to disinfect the activated carbon, however, each process has drawbacks that make the process unattractive.
Standard disinfectants such as chlorine have been utilized for many years in an attempt to disinfect activated carbon. Chlorine however will react chemically with the activated carbon structure, over time weakening the carbon skeleton and therefore physically degrading the activated carbon. The reaction of chlorine with activated carbon is also kinetically very rapid; therefore, the entire bed of activated carbon is not disinfected. The use of high levels of chlorine will also cause the generation of trihalomethanes, which are known carcinogens.
Various caustic solutions and acids have also been utilized over the years to disinfect activated carbon, with varying degrees of success. The process relies on a significant change in the pH of the solution to disinfect the activated carbon. Because of using high or low pH solutions, large volumes of acidic or basic waste is generated, which must be neutralized for safe disposal. Materials of construction must also be taken into account since the low or high pH can be corrosive to various metals or concrete. The disposal and materials of construction issues prevent disinfection by caustic solution or acid from being technically or economically feasible.
Other disinfection methods such as steaming are routinely utilized in industries such as brewing and bottling. The process involves the introduction of steam to a bed of activated carbon, holding the carbon bed at temperature for several hours, cooling, and rinsing prior to reestablishing flow to the carbon unit. This process although technically feasible, is not practical for various industries such as large municipal drinking water systems.
All of the prior art methods for disinfection of activated carbon have certain disadvantages, which make the processes unattractive from either a technical or economical basis. Chief among them is the generation of various waste products, which require disposal or create corrosion issues.
Accordingly, it is the object of the present invention to provide an improved process for the disinfection of activated carbon using peroxide-containing materials. It is a further the object of this invention to provide a disinfection process that does not generate harmful by-products, generate waste products requiring disposal, or cause materials of construction issues.